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Insulating Walls in a Hot-Humid Climate

AndyATL | Posted in General Questions on

Hi Everyone,
This site has taught me so much and will continue to- I’m very thankful for its existence!

So, what had happened was… I bought a house “as is” and the person renovating it quit halfway through and right now I’m at the point of insulating before sheetrock goes up.

Firstly, I’m in climate 3a- hot and humid summers and mild winters (atlanta area). My house is a 1963 ranch with a crawlspace, exterior is brick and there’s a black fiber board behind that with an airgap between the two. The walls are framed with 2×4’s and I’m also under a flight path so I want to mitigate sound as much as possible.

1- what is this black board? Is it okay that there’s nails poking through and how do I patch spots that need it? There’s not many but there are a few.

2- I have been gathering materials but I’ve read so much online that I’ve confused myself and what I need is for someone knowledgeable to say “okay, this is what you want to do and in this order” instead of leaving me with choices and options because I’m really overwhelmed by all the choices.

I have various foam boards (foamular and two different types of foil-faced- 1/2″ and 1″)  but I don’t know how to use them properly- I am terrified of doing the wrong thing and having big problems to deal with down the road. Help! I plan on using mineral or rockwool insulation for the exterior walls but should I incorporate some of this foam board? how, and in what order?

The insulation is the only thing I’m doing by myself, btw. Everything else is being done by professionals.

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  1. user-2310254 | | #1


    1. It's probably fiberboard or exterior drywall. You don't need to worry about nails but should caulk or tape any holes. Since all the walls are open, you also have the opportunity to air seal the walls and windows, which will help with mitigating noise. Here is one article that should be helpful:

    2. I would fill the wall framing with high density fiberglass or rockwool batts. You might be able to use the rigid foam on the walls of your crawlspace. If you have room to work, it would be a good time to convert it into a sealed space. For more on this topic, see

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